1. Field of the Invention
The present invention relates to relative motion stabilizers, and more particularly to devices including one or more biasing elements and telescoping body assemblies for yieldingly holding a load in a quasi-normal or quasi-centered position.
2. Discussion of the Related Art
There is a long standing need for a stabilizer for stabilizing the movement of a load that is movable relative to another load or a relatively fixed support. Such a stabilizer should yieldingly hold the load in a normal position. In many instances, the normal position is a centered position in a range of movement of the movable load. The stabilizer should include a reaction unit having a biasing element acting through an assembly to permit the load to be displaced from the normal position and to resiliently bias the load to return from the displaced position back toward the normal position.
There are numerous and varied applications for a motion stabilizer of this kind. One example of an application exhibiting such a need is the steering system of a large vehicle such as a truck or recreational vehicle. In this application, the motion stabilizer urges the steering gear toward a normal or centered position in which the vehicle travels straight ahead and permits the steering gear to be displaced so that the vehicle can be turned. In a vehicle application, a motion stabilizer should be able to hold the vehicle under control in the presence of cross winds, road irregularities, tire blowouts, and the like. Other applications for motion stabilizers include conveyors and manufacturing equipment, power boats, vehicles of many types and trailer hitch systems. A motion stabilizer can provide advantages in many situations where a movable load must be yieldingly held in a centered or normal position.
Many stabilizing or centering systems have been developed or proposed in the past. For example, U.S. Pat. Nos. 1,223,573 and 4,406,473 disclose vehicle steering stabilizer systems using a pair of coil springs urging a component of the vehicle steering linkage toward a centered or normal position. In another example, U.S. Pat. No. 4,822,012 discloses a bidirectional steering stabilizer having a single spring and a damper for yieldably biasing the wheels of a vehicle toward a straight ahead direction. Although these systems are relatively simple in that they are mechanical devices with relatively few parts, they suffer from disadvantages including interfering with the operator""s ability to control the vehicle in a natural way and a lack of the ability to accommodate a variety of types of springs and reaction units and the ability to easily adjust the stabilizer to match the requirements of a particular vehicle or application.
Another approach that has been used in the past is to provide a complex hydraulic and pneumatic system for assisting the power steering system of a large vehicle in holding the steering linkage and wheels on center. One example of a system of this type is the Howard Power Center Steering System sold by River City Products, Inc. of San Antonio, Tex. Although this steering control system performs well, it is subject to the disadvantages of complexity and large expense, and it is not easily adaptable to a variety of differing applications.
One of the major shortcomings of prior art stabilizing and centering systems, particularly for applications involving vehicle steering stabilizer systems, is the inability to dynamically adjust the desired xe2x80x9ccenteredxe2x80x9d position of the steering stabilizer systems. For example, when a steering stabilizer system is being installed on a large truck or motorhome, the apparent centered position would be when the front wheels of the vehicle are turned such that they would appear to cause the vehicle to follow a straight path. However, experience has demonstrated that straight ahead as determined visually is not necessarily straight ahead under actual operating conditions of the vehicle. As a result, after a test drive, the steering stabilizer system may need to be arbitrarily adjusted in an attempt to more accurately guestimate the location of the true operational center for the steering stabilizer system.
As another example of the need for a dynamically adjustable steering stabilizer system, if a heavy load is shifted more toward one side of a moving vehicle, or if one or more tires is not properly inflated on one side of the moving vehicle, or if a tire goes flat or blows out, or if the moving vehicle is being subjected to a severe cross-wind, the vehicle will tend to veer toward one side forcing the driver of the vehicle to counter-steer to compensate for the imbalance. In other words, under the changed conditions, the centering position originally perceived for the steering stabilizer system has been displaced, at least temporarily. As a result, the steering stabilizer system which was intended to assist the driver has become a detriment to the driver and instead of assisting, in some cases works against, the driver while he is attempting to navigate the vehicle straight forwardly along the roadway.
What is needed is a steering stabilizer system wherein the centering and stabilizing characteristic thereof can be dynamically altered if necessary to compensate for changed or changing conditions, even as the vehicle is actually being driven along a roadway.
The principal objects of the invention include: providing an apparatus and method that provides an adjustable motion stabilizer for a vehicle; providing such an apparatus and method that can be dynamically adjustable while the vehicle is being operated; and generally providing such an apparatus and method that is reliable in performance, capable of long lasting life, and particularly well adapted for the proposed usages thereof.
Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention.
A principal object of the present invention is to provide an improved motion stabilizer for controlling relative movement of two relatively movable loads. Other objects are to provide a motion stabilizer including a biasing element and a telescoping body assembly for yieldingly urging a load member toward a normal or centered position; to provide a motion stabilizer that can extend the utility of a reaction unit such as a gas spring by doubling its effective stroke and providing a two-way action; to provide a motion stabilizer that can accommodate many types of reaction units such as compression or extension springs of several types, dampers and combinations of springs and dampers; to provide a motion stabilizer that can be tailored to optimize the operating characteristics required for many different applications such as vehicle steering systems and industrial applications; to provide a motion stabilizer that is bidirectional and symmetrical in operation; and to provide a motion stabilizer overcoming disadvantages of motion stabilizing and centering systems used in the past.
In brief, in accordance with the invention, there is provided a motion stabilizer for controlling motion between first and second relatively movable load members. The motion stabilizer includes an elongated body assembly defining an axially extending internal chamber. The body assembly includes axially spaced first and second attachment members for connection to the load members. A reaction unit is captured within the chamber and has an axial length that varies between first and second lengths. The body assembly has an axial length variable in response to relative motion of the attachment members. The body assembly has a normal position in which the reaction unit has the first length and in which the attachment structures are separated by a predetermined distance. The body assembly includes means for varying the axial length of the reaction unit from the first length toward the second length in response to relative axial movement of the attachment structures in either axial direction from the normal position. The body assembly includes at least a radially inner body member and a radially outer telescoped body member, the body members being axially movable relative to one another. The radially inner body member defines at least part of the chamber and has a force transfer portion engageable with the reaction unit. The inner body member includes an elongated axial opening providing access from the chamber to the radially outer body member. The reaction unit includes a force transfer portion extending radially from the chamber through the axial opening for engagement with the radially outer body member.
In addition, the motion stabilizer includes a centering adjustment mechanism to compensate for changed conditions that force a driver apply a counter-steering force to overcome undesirable or uncontrollable adverse steering conditions. The centering mechanism includes a gas-spring assembly for adjusting the xe2x80x9ccenterxe2x80x9d of the motion stabilizer, a locking mechanism for releasably locking the gas-spring assembly, a releasing mechanism for unlocking the locking mechanism, and a control mechanism for dynamically controlling the releasing mechanism.